People often exercise while lying on a bench, as by lifting weights with their hands. Such exercise usually does not exercise the person's core muscles. An exercise device that enabled a person lying on a bench, to exercise the person's core muscles would be of value.
My earlier U.S. Pat. No. 7,645,221 describes an exercise device that has a platform supported on coil springs, that encourages a person to exercise by shifting his weight to control platform tilt. However, that device does not provide sufficient exercise for the muscles of the chest.